An Automated Conversion Between Selected Robot Kinematic Representations

This paper presents a methodology that forms an automated tool for robot kinematic representation conversion, called the RobKin Interpreter. It is a set of analytical algorithms that can analyze an input robot representation, express the joints globally in matrix form, and map to other representations such as standard Denavit-Hartenberg parameters, Roll-Pitch-Yaw angles with translational displacement, and Product of Exponentials with a possibility to generate a URDF (Universal Robot Description Format) file from any of them. It works for revolute and prismatic joints and can interpret even arbitrary kinematic structures that do not have orthogonally placed joints

Implementation of explosion safety regulations in design of a mobile robot for coal mines

The article focuses on specific challenges of the design of a reconnaissance mobile robotic system aimed for inspection in underground coal mine areas after a catastrophic event. Systems that are designated for these conditions must meet specific standards and regulations. In this paper is discussed primarily the main conception of meeting explosion safety regulations of European Union 2014/34/EU (also called ATEX-from French "Appareils destines a etre utilises en ATmospheres Explosives") for Group I (equipment intended for use in underground mines) and Category M1 (equipment designed for operation in the presence of an explosive atmosphere). An example of a practical solution is described on main subsystems of the mobile robot TeleRescuera teleoperated robot with autonomy functions, a sensory subsystem with multiple cameras, three-dimensional (3D) mapping and sensors for measurement of gas concentration, airflow, relative humidity, and temperatures. Explosion safety is ensured according to the Technical Report CLC/TR 60079-33 "s" by two main independent protections-mechanical protection (flameproof enclosure) and electrical protection (automatic methane detector that disconnects power when methane breaches the enclosure and gets inside the robot body).Web of Science811art. no. 230

Řízení manipulátoru servisního robotu kopírováním pohybů ruky operátora v prostoru

This paper describes a practical solution of the problem of controlling a manipulator arm of a mobile service robot by a human operator using the natural method of following the movements of the operator’s hand in space. This system is a part of the complex control system of the mobile robot Hercules developed by the Department of robotics and is used to control its 3-degree-of-freedom manipulator with a gripper, but can be after some modifications applied to any similar arm with up to 6 degrees of freedom.Článek popisuje praktické řešení problematiky řízení manipulační nadstavby mobilního servisního robotu lidským operátorem pomocí přirozené metody kopírování pohybu operátorovy ruky v prostoru. Systém je součástí komplexního řídicího systému mobilního robotu Hercules navrženého katedrou robototechniky a je využíván pro řízení manipulátoru s 3 stupni volnosti a chapadlem, který je na tomto robotu umístěn. Po několika úpravách může být však použit pro řízení libovolného podobného ramene s až 6 stupni volnosti

TESTING OF GLUED JOINTS ON PLASTIC PARTS MANUFACTURED USING FFF TECHNOLOGY

The article focuses on the testing of glued joints of plastic parts manufactured by 3D rapid prototyping, using the Fused Filament Fabrication technology. The first part of the article describes the suitability of using a glued joint. Then follows a brief description of the plastic materials used for the manufacturing of the testing samples. The materials include not only the common types, such as Polylactide, Polyethylene Terephthalate, Acrylonitrile Butadiene Styrene, but also Thermoplastic Polyurethane, which has a high elasticity and is usually described as a flexible material. The main section of the article deals with the testing of glued joints on a tensometric machine, which produces stress-strain curves. The shear strength of the joints is evaluated. For each material, multiple samples are prepared with different orientation of individual layers created by the 3D printing process. The impact of the orientation of the layers on the resulting strength of the glued joint is also evaluated. The final section of the article presents comparison and evaluation of the results –analyses of cracks, the impact of the orientation of the layers and the impact of individual materials. The experiment proved the independence of the orientation of the layers on the strength of the glued joint. It was also found out during the experiment that the use of a common adhesive on a flexible material was unsuitable

Generating synthetic depth image dataset for industrial applications of hand localization

In this paper, we focus on the problem of applying domain randomization to produce synthetic datasets for training depth image segmentation models for the task of hand localization. We provide new synthetic datasets for industrial environments suitable for various hand tracking applications, as well as ready-to-use pre-trained models. The presented datasets are analyzed to evaluate the characteristics of these datasets that affect the generalizability of the trained models, and recommendations are given for adapting the simulation environment to achieve satisfactory results when creating datasets for specialized applications. Our approach is not limited by the shortcomings of standard analytical methods, such as color, specific gestures, or hand orientation. The models in this paper were trained solely on a synthetic dataset and were never trained on real camera images; nevertheless, we demonstrate that our most diverse datasets allow the models to achieve up to 90% accuracy. The proposed hand localization system is designed for industrial applications where the operator shares the workspace with the robot.Web of Science10997449973

Dálkové řízení elektrického invalidního vozíku

This paper describes modifications and completion of the control system of electric wheelchair in order to serve as a platform for remote-controlled mobile robot. The main task was to provide remote control of this mobile robot, because the existing control system works only with a wired controller. Due to the unavailability of appropriate documentation, it was necessary to analyze the original control system and to determine the possibility of its connection to a superior control system on the operator’s station. It was also needed to design and make an electronic module, which would implement the found solution. Through this module it is possible to send movement commands to the robot chassis via wireless links and thus to ensure the remote control at distance of up to several kilometers.Článek se zabývá popisem modifikace a doplnění řídicího systému elektrického invalidního vozíku tak, aby posloužil jako platforma pro dálkově ovládaný mobilní robot. Hlavním úkolem bylo zajistit dálkové ovládání tohoto mobilního robotu, protože stávající řídicí systém pracuje pouze s drátovým ovladačem. Vzhledem k nedostupnosti vhodné dokumentace bylo potřeba analyzovat původní řídicí systém a vymezit možnosti jeho napojení na nadřazený řídicí systém stanoviště operátora mobilního robotu. Dále bylo potřeba navrhnout a zhotovit elektronický modul, který bude stanovené řešení realizovat. Prostřednictvím tohoto modulu je tak umožněno zasílat povely k pohybu robotického podvozku prostřednictvím bezdrátového pojítka a zajistit tak jeho dálkové ovládání na vzdálenost až několik kilometrů

Camera arrangement optimization for workspace monitoring in human-robot collaboration

Human-robot interaction is becoming an integral part of practice. There is a greater emphasis on safety in workplaces where a robot may bump into a worker. In practice, there are solutions that control the robot based on the potential energy in a collision or a robot re-planning the straight-line trajectory. However, a sensor system must be designed to detect obstacles across the human-robot shared workspace. So far, there is no procedure that engineers can follow in practice to deploy sensors ideally. We come up with the idea of classifying the space as an importance index, which determines what part of the workspace sensors should sense to ensure ideal obstacle sensing. Then, the ideal camera positions can be automatically found according to this classified map. Based on the experiment, the coverage of the important volume by the calculated camera position in the workspace was found to be on average 37% greater compared to a camera placed intuitively by test subjects. Using two cameras at the workplace, the calculated positions were 27% more effective than the subjects' camera positions. Furthermore, for three cameras, the calculated positions were 13% better than the subjects' camera positions, with a total coverage of more than 99% of the classified map.Web of Science231art. no. 29

Multirepresentations and multiconstraints approach to the numerical synthesis of serial kinematic structures of manipulators

This paper presents a set of algorithms for the synthesis of kinematic structures of serial manipulators using multiple constraint formulation and provides a performance comparison of different kinematic representations, the Denavit-Hartenberg notation, the Product of Exponentials (screws), and Roll-Pitch-Yaw angles with translation parameters. Synthesis is performed for five given tasks, and both revolute and prismatic joints can be synthesized. Two different non-linear programming optimization algorithms were used to support the findings. The results are compared and discussed. Data show that the choice of the constraint design method has a significant impact on the success rate of optimization convergence. The choice of representation has a lower impact on convergence, but there are differences in the optimization time and the length of the designed manipulators. Furthermore, the best results are obtained when multiple methodologies are used in combination. An arbitrary manipulator was designed and assembled based on a trajectory in the collision environment to demonstrate the advantages of the proposed methodology. The input/output data and synthesis methodology algorithms are provided through an open repository.Web of Science10689516893

Distributed camera subsystem for obstacle detection

This work focuses on improving a camera system for sensing a workspace in which dynamic obstacles need to be detected. The currently available state-of-the-art solution (MoveIt!) processes data in a centralized manner from cameras that have to be registered before the system starts. Our solution enables distributed data processing and dynamic change in the number of sensors at runtime. The distributed camera data processing is implemented using a dedicated control unit on which the filtering is performed by comparing the real and expected depth images. Measurements of the processing speed of all sensor data into a global voxel map were compared between the centralized system (MoveIt!) and the new distributed system as part of a performance benchmark. The distributed system is more flexible in terms of sensitivity to a number of cameras, better framerate stability and the possibility of changing the camera number on the go. The effects of voxel grid size and camera resolution were also compared during the benchmark, where the distributed system showed better results. Finally, the overhead of data transmission in the network was discussed where the distributed system is considerably more efficient. The decentralized system proves to be faster by 38.7% with one camera and 71.5% with four cameras.Web of Science2212art. no. 458

Method for robot manipulator joint wear reduction by finding the optimal robot placement in a robotic cell

We describe a method for robotic cell optimization by changing the placement of the robot manipulator within the cell in applications with a fixed end-point trajectory. The goal is to reduce the overall robot joint wear and to prevent uneven joint wear when one or several joints are stressed more than the other joints. Joint wear is approximated by calculating the integral of the mechanical work of each joint during the whole trajectory, which depends on the joint angular velocity and torque. The method relies on using a dynamic simulation for the evaluation of the torques and velocities in robot joints for individual robot positions. Verification of the method was performed using CoppeliaSim and a laboratory robotic cell with the collaborative robot UR3. The results confirmed that, with proper robot base placement, the overall wear of the joints of a robotic arm could be reduced from 22% to 53% depending on the trajectory.Web of Science1112art. no. 539